<jats:sec id="S2056472423000054_sec_a1"> <jats:title>Background</jats:title> <jats:p>Previous studies have not investigated response rates after electroconvulsive therapy (ECT) in patients with non-psychotic treatment-resistant depression (TRD).</jats:p> </jats:sec> <jats:sec id="S2056472423000054_sec_a2"> <jats:title>Aims</jats:title> <jats:p>To assess and compare the response rate of ECT for patients with TRD and non-TRD, in a large and clinically representative patient sample.</jats:p> </jats:sec> <jats:sec id="S2056472423000054_sec_a3" sec-type="methods"> <jats:title>Method</jats:title> <jats:p>Patients aged ≥18 years, who were treated for a unipolar, non-psychotic depressive episode with at least one ECT session as part of a first-time, index ECT series between 1 January 2011 and 31 December 2017 were included from the Swedish National Quality Register for ECT. Patients who had initiated a third consecutive trial of antidepressants or add-on medications before start of ECT were classified as having TRD. Patients not meeting criteria for TRD were classified as non-TRD. The main outcome was response to ECT according to the Clinical Global Impressions – Improvement Scale (CGI-I), scored as 1 or 2 (‘very much’ or ‘much improved’ after ECT, respectively). Logistic regression was used to compare outcome measures between TRD and non-TRD, adjusting for potential confounders.</jats:p> </jats:sec> <jats:sec id="S2056472423000054_sec_a4" sec-type="results"> <jats:title>Results</jats:title> <jats:p>A total of 4244 patients were included. Of these, 1121 patients had TRD and 3123 patients had non-TRD. The CGI-I response rate was 65.9% in the TRD group compared with 75.9% in the non-TRD group (adjusted odds ratio 0.64, 95% CI 0.54–0.75). Older age and more severe depression were predictors of response in patients with TRD.</jats:p> </jats:sec> <jats:sec id="S2056472423000054_sec_a5" sec-type="conclusions"> <jats:title>Conclusions</jats:title> <jats:p>A clear majority of patients with TRD, as well as patients with non-TRD, responded to ECT, although the response rate was somewhat lower for TRD.</jats:p> </jats:sec>